Naturalization (or naturalisation) is the legal act or process by which a non-citizen in a country may acquire citizenship or nationality of that country. It may be done by a statute, without any effort on the part of the individual, or it may involve an application and approval by legal authorities. The rules of naturalization vary from country to country and typically include a minimum legal residency requirement, and may specify other requirements such as knowledge of the national dominant language or culture, a promise to obey and uphold that country's laws. An oath or pledge of allegiance is also sometimes required. Some countries also require that the person renounce any other citizenship that they currently hold, forbidding dual citizenship, but whether this renunciation actually causes loss of the person's original citizenship, as seen by the host country and by the original country, will again depend on the laws of the countries involved.

The massive increase in population flux due to globalization and the sharp increase in the numbers of refugees following World War I created a large number of stateless persons, people who were not citizens of any state. In some rare cases, procedures of mass naturalization were passed. As naturalization laws had been designed to cater for the relatively few people who had voluntarily moved from one country to another (expatriates), western democracies were not ready to naturalize the massive influx of stateless people which followed massive denationalizations and the expulsion of ethnic minorities from newly created nation states in the first part of the 20th century, but they also counted the (mostly aristocratic) Russians who had escaped the 1917 October Revolution and the war communism period, and then the Spanish refugees. As Hannah Arendt pointed out, internment camps became the "only nation" of such stateless people, since they were often considered "undesirable" and were stuck in an illegal situation (their country had expelled them or deprived them of their nationality, while they had not been naturalized, thus living in a judicial no man's land).

Since World War II, the increase in international migrations created a new category of refugees, most of them economic refugees. For economic, political, humanitarian and pragmatic reasons, many states passed laws allowing a person to acquire their citizenship after birth (such as by marriage to a national – jus matrimonii – or by having ancestors who are nationals of that country), in order to reduce the scope of this category. However, in some countries this system still maintains a large part of the immigrated population in an illegal status, albeit some massive regularizations (in Spain by José Luis Zapatero's government and in Italy by Berlusconi's government).

There has always been a distinction in the law of England and Wales between the subjects of the monarch and aliens: the monarch's subjects owed the monarch allegiance, and included those born in his or her dominions (natural-born subjects) and those who later gave him or her their allegiance (naturalised subjects). Today, the requirements for naturalisation as a citizen of the United Kingdom depend on whether or not one is the spouse or civil partner of a citizen. An applicant who is a spouse or civil partner of a British citizen must:

been outside of the UK no more than 90 days during the one-year period prior to filing the application.

show sufficient knowledge of life in the UK, either by passing the Life in the United Kingdom test or by attending combined English language and citizenship classes. Proof of this must be supplied with one's application for naturalisation. Those aged 65 or over may be able to claim exemption.

In the United States of America, the Constitution gives Congress the power to prescribe a uniform rule of naturalization, which is administered by state courts. There was some confusion about which courts could naturalize; the final ruling was that it could be done by any "court of record having common-law jurisdiction and a clerk (prothonotary) and seal."

The Constitution also mentions "natural born citizen". The first naturalization Act (drafted by Thomas Jefferson) used the phrases "natural born" and "native born" interchangeably.

The Constitution does not mandate race-neutral naturalization. Until 1952, the Naturalization Acts allowed only white persons to become naturalized citizens (except for two years in the 1870s which the Supreme Court declared to be a mistake).[clarification needed]

Naturalization is also mentioned in the Fourteenth Amendment. The Supreme Court, in the case of Minor v. Happersett explained who the citizens of the United States were before its adoption, the Court said, Before the 14th Amendment, "the Constitution of the United States did not in terms prescribe who should be citizens [of the United States] or of the several states, yet there were necessarily such citizens without such provision. Additions might always be made to the citizenship of the United States in two ways: first, by birth, and second, by naturalization". Before the U.S. Constitution was adopted, individual states set their own standards for citizenship; After Adoption, all state citizens "became ipso facto a citizen" of the United States and all children born in the United States "of parents who were its citizens became themselves, upon their birth, citizens [of the United States]. These were natives or natural-born citizens, as distinguished from aliens or foreigners.". The 14th Amendment states that "all persons born or naturalized in the United States and subject to the jurisdiction thereof shall be citizens of the United States and of the State in which they reside". The Minor v. Happersett Court went on to say, "Some authorities go further and include as citizens children born within the jurisdiction without reference to the citizenship of their parents. As to this class there have been doubts, but never as to the first". The Supreme Court later, in the case of Afroyim v. Rusk, interpreted this clause to imply that a naturalized citizen cannot be subsequently deprived of U.S. citizenship involuntarily.

An 1862 law allowed honorably discharged Army veterans of any war to petition for naturalization, without having filed a declaration of intent, after only one year of residence in the United States. An 1894 law extended the same privilege to honorably discharged five-year veterans of the Navy or Marine Corps. Over 192,000 aliens were naturalized between May 9, 1918, and June 30, 1919, under an act of May 9, 1918. Laws enacted in 1919, 1926, 1940, and 1952 continued preferential treatment provisions for veterans.[1]

Passage of the Fourteenth Amendment meant that, in theory, all persons born in the United States, and subject to the jurisdiction thereof, are citizens regardless of race. Citizenship by birth in the United States, however, was not initially granted to Asians until 1898, when the Supreme Court, in the case of United States v. Wong Kim Ark held that the Fourteenth Amendment did apply to Asians born in the United States to Alien parents who have a permanent domicile and residence in the United States.

The enabling legislation for the naturalization aspects of the Fourteenth Amendment was the Naturalization Act of 1870, which allowed naturalization of "aliens of African nativity and to persons of African descent", but is silent about other races. The 1882 Chinese Exclusion Act banned Chinese workers and specifically barred them from naturalization. The Immigration Act of 1917, (Barred Zone Act) extended those restrictions to almost all Asians.

The 1922 Cable Act specified that women marrying aliens ineligible for naturalization lose their US citizenship. At the time, all Asians were ineligible for naturalization. The Immigration Act of 1924 barred entry of all those ineligible for naturalization, which again meant non-Filipino Asians.

Following the Spanish American War in 1898, Philippine residents were classified as U.S. nationals, and the 1917 Jones–Shafroth Act granted U.S. citizenship to citizens of Puerto Rico. But the 1934 Tydings–McDuffie Act (or Philippine Independence Act) reclassified Filipinos as aliens, and set a quota of 50 immigrants per year, and otherwise applying the Immigration Act of 1924 to them. The quotas did not apply to Filipinos who served in the United States Navy, which actively recruited in the Philippines at that time.

Asians were first permitted naturalization by the 1943 Magnuson Act, which repealed the Chinese Exclusion Act. India and the Philippines were allowed 100 annual immigrants under the 1946 Filipino Naturalization Act. The War Brides Act of 1945 permitted soldiers to bring back their foreign wives and established precedent in naturalization through marriage. The 1952 Immigration and Nationality Act (better known as the McCarran–Walter Act) lifted racial restrictions, but kept the quotas in place. The Immigration Act of 1965 finally allowed Asians and all persons from all nations be given equal access to immigration and naturalization.

Illegal immigration became a major issue in the United States at the end of the 20th century. The Immigration Reform and Control Act of 1986, while tightening border controls, also provided the opportunity of naturalization for illegal aliens who had been in the country for at least four years. Today, lawful permanent resident aliens can apply for naturalization in the United States after five years, unless they continue to be married to a U.S. citizen, in which case they can apply after three years of permanent residency.[2]

The Child Citizenship Act of 2000 streamlined the naturalization process for children adoptedinternationally. A child under age 18 who is adopted by at least one U.S. citizen parent, and is in the custody of the citizen parent(s), is now automatically naturalized once admitted to the United States as an immigrant or when legally adopted in the United States, depending on the visa under which the child was admitted to the United States.

The Indian citizenship and nationality law and the Constitution of India provides single citizenship for the entire country. The provisions relating to citizenship at the commencement of the Constitution are contained in Articles 5 to 11 in Part II of the Constitution of India. Relevant Indian legislation is the Citizenship Act 1955, which has been amended by the Citizenship (Amendment) Act 1986, the Citizenship (Amendment) Act 1992, the Citizenship (Amendment) Act 2003, and the Citizenship (Amendment) Ordinance 2005. The Citizenship (Amendment) Act 2003 received the assent of the President of India on 7 January 2004 and came into force on 3 December 2004. The Citizenship (Amendment) Ordinance 2005 was promulgated by the President of India and came into force on 28 June 2005.

Following these reforms, Indian nationality law largely follows the jus sanguinis (citizenship by right of blood) as opposed to the jus soli (citizenship by right of birth within the territory).

The People's Republic of China gives citizenship to persons with one or two parents with Chinese nationality who have not taken residence in other countries. The country also gives citizenship to persons born on its territory to stateless persons who have settled there. Furthermore, individuals may apply for nationality if they have a near relative with Chinese nationality, if they have settled in China, or if they present another legitimate reason.[3]

The naturalization process starts with a written application. Applicants must submit three copies, written with a ball-point or fountain pen, to national authorities, and to provincial authorities in the Ministry of Public Security and the Public Security Bureau. Applicants must also submit original copies of a foreign passport, a residence permit, a permanent residence permit, and four two-and-a-half inch long pictures. According to the conditions outlined in the Nationality Law of the People's Republic of China, authorities may also require "any other material that the authority believes are related to the nationality application".[4]

Indonesian nationality regulated by Law No. 12/2006 (UU No. 12 Tahun 2006). The Indonesian nationality law is based on jus sanguinis and jus soli. The Indonesian nationality law does not recognize dual citizenship except for persons under the age of 18 (single citizenship principle). After reaching 18 years of age individuals are forced to choose one citizenship (limited double citizenship principle).[5]

A foreign citizen can apply to become an Indonesian citizen with the following requirements:

Age 18 or older, or married

Resided in Indonesia for a minimum of 5 consecutive years or 10 non-consecutive years

Israel's Declaration of Independence was made on 14 May 1948, the day before the British Mandate was due to expire as a result of the United Nations Partition Plan.[6] The Israeli parliament created two laws regarding immigration, citizenship and naturalization: the Law of Return and the Israeli nationality law.[7] The Law of Return, enacted on July 15, 1950, gives Jews living anywhere in the world the right to immigrate to Israel. This right to immigrate did not and still does not grant citizenship. In fact, for four years after Israel gained independence, there were no Israeli citizens.[7]

On July 14, 1952, the Israeli parliament enacted the Israeli Nationality Law.[7] The Nationality Law naturalized all citizens of Mandated Palestine, the inhabitants of Israel on July 15, 1952, and those who had legally resided in Israel between May 14, 1948, and July 14, 1952. The law further clarified that naturalization was available to immigrants who had arrived before Israel's creation, immigrants who arrived after statehood was granted, and those who did not come to Israel as immigrants but have since expressed desire to settle in Israel, with restriction. Naturalization applicants must also meet the following requirements: be over 18 years of age, have resided in Israel for three out of the five preceding years, have settled or intend to settle permanently in Israel, have some knowledge of Hebrew, and have renounced prior nationality or demonstrated ability to renounce nationality after becoming a citizen of Israel.[7]

Because of Israel's relatively new and culturally mixed identity, Israel does not grant citizenship to persons born on Israeli soil. Instead, the government chose to enact a jus sanguinis system, with the naturalization restrictions listed above. There is currently no legislation on second-generation immigrants (those born in Israel to immigrant parents). Furthermore, foreign spouses can apply for citizenship through the Minister of the Interior, but have a variety of restrictions and are not guaranteed citizenship.[8]

Naturalization in Russia is guided by articles 13 and 14 of the federal law “About Citizenship of Russian Federation” passed on May 31, 2002. Citizenship of Russia can be obtained in general or simplified order. To become a citizen in general order, one must be 18 years of age or older, continuously live in Russia as a permanent resident for at least 5 years (this term is limited to 1 year for valued specialists, political asylum seekers and refugees), have legal means of existence, promise to obey the laws and Constitution of Russia and be fluent in Russian language.

There is also a possibility to naturalize in a simplified order, in which certain requirements will be waived. Eligible for that are persons, at least one parent of whom is a Russian citizen living on Russian territory; persons, who lived on the territories of the former Soviet republics but never obtained citizenships of those nations after they gained independence; persons, who were born on the territory of RSFSR and formerly held Soviet citizenship; persons married to Russian citizens for at least 3 years; persons, who served in Russian Armed Forces under contract for at least 3 years; parents of mentally incapacitated children over 18 who are Russian citizens; participants of the State Program for Assisting Compatriots Residing Abroad; and some other categories.[9]

Chapter 2 of the South African Citizenship Act, enacted on October 6, 1995, defines who is considered a naturalized citizen at the time of the act and also outlines the naturalization process for future immigrants.[10]

Any person who immediately prior to the commencement of the act had been a South African citizen via naturalization, had been deemed to be a South African citizen by registration, or had been a citizen via naturalization of any of the former states now composing South Africa is now considered to be a naturalized citizen of South Africa.[10]

Those wishing to apply for naturalization in the future must apply to the Minister of Home Affairs and must meet a slew of requirements. First, naturalization applicants must be over the age of 18 and must have been a permanent resident of South Africa for one year prior to application and for four out of the eight years prior to application. Applicants must also demonstrate good character and knowledge of the basic responsibilities and privileges of a South African citizen. The ability to communicate in one of the official languages of South Africa is also required. Applicants must show the intention to reside in South Africa after naturalization, and they are required to make a declaration of allegiance.[10]

Being a naturalized South African citizen is a privilege, not a right. Even after meeting all the requirements and going through the naturalization process, the minister holds the right to deny citizenship.[11] Foreign spouses of South African citizens can apply for naturalization after two years of marriage, but is subject to potential denial of the minister. The minister can also grant citizenship to minors, if their parent applies for them.[10]

The minister also holds the power to revoke naturalization at any time for specific reasons listed in the Act. Reasons for revoking the naturalization certificate include marrying someone who is a citizen of another country and holding citizenship in another country, or applying for citizenship of another country without prior authorization for retention of citizenship.[11] If a permanent resident is denied naturalization, he or she must wait at least one year before reapplying.[10]

The following list is a short summary of the duration of legal residence before a national of a foreign state, without any cultural, historical, or marriage ties or connections to the state in question, can request citizenship under that state's naturalization laws.

Andorra: 20 years permanent resident, unless the applicant has spent all of his mandatory education in Andorra in which case 10 years permanent residence.[13]

Angola: 10 years continuous as a permanent resident immediately before the application (dual citizenship is allowed)[14]

Argentina: 2 years continuous as a permanent resident immediately before the application (dual citizenship is allowed)[15]

Australia: 4 years of legal residency in Australia including 1 year as a permanent resident immediately prior to making an application (dual citizenship is allowed)[16]

Austria: 10 years residence, with exceptions for those born in Austria, citizens of another EEA country, refugees or "exceptionally integrated" in which case it is 6 years. (Dual citizenship not normally permitted.)[17]

Bulgaria: The applicant should be at least 18 years old; have permission for permanent or for long-term residence in Bulgaria since at least 5 years;[26] have not been investigated or sentenced by the Bulgarian authorities; have income or occupation; be able to speak and write in Bulgarian; renounce previous citizenship (not applicable to citizens of the EU and EEA countries, Switzerland and countries with reciprocity agreement with Bulgaria; dual citizenship is allowed for them).

Ireland: 5 years over the last 9 years, including at least 1 year before applying.[36] Dual citizenship is allowed, however Irish citizenship can be revoked if a naturalized citizen obtains citizenship of another state (other than automatic citizenship by marriage) subsequent to naturalization.

New Zealand: 5 years continuous (reside in NZ for at least 240 days in each of those 5 years, 1,350 days in total) as a permanent resident immediately before the application (dual citizenship is allowed)[42]

Norway: 7 years out of the previous 10 (with out-of-realm vacations of up to 2 months per year) as a permanent resident immediately before the application (dual citizenship is permitted under certain conditions)[43]

South Korea: 5 years continuous. 2 years continuous if married to a South Korean national. (dual citizenship is only allowed for foreign born nationals who married to a Korean citizen, Korean men holding dual citizenship by birth served in the Korean Armed Forces, Korean women with multiple nationalities by birth who has vowed her intention not to exercise her foreign nationality in the Republic of Korea and overseas Koreans at least 65 years of age)[53]

Sweden: 5 years continuous (dual citizenship is allowed). 4 years continuous for stateless people and refugees.[54]

Switzerland: 12 years (the years between the age of 10 and 20 count double). (dual citizenship is allowed)[55]

A few rare mass naturalization processes have been implemented by nation states. In 1891, Brazil granted naturalization to all aliens living in the country.[58] In 1922, Greece massively naturalized all the Greek refugees coming back from Turkey. The second massive naturalization process was in favor of Armenian refugees coming from Turkey, who went to Syria, Lebanon or other former Ottoman countries. Reciprocally, Turkey massively naturalized the refugees of Turkish descent or other ethnic backgrounds in Muslim creed from these countries during a redemption process.

After annexation of the territories east of the Curzon line by the Soviet Union in 1945, Soviets naturalized en masse all the inhabitants of those territories—including ethnic Poles, as well as its other citizens who had been deported into the Soviet Union, mainly to Kazakhstan. Those persons were forcibly naturalized as Soviet citizens.[citation needed] Later on, Germany granted to the ethnic German population in Russia and Kazakhstan full citizenship rights. Poland has a limited repatriation program in place.

The most recent massive naturalization case resulted from the Argentine economic crisis in the beginning of the 21st century. Existing or slightly updated right of return laws in Spain and Italy allowed many of their diasporic descendants to obtain—in many cases to regain—naturalization in virtue of jus sanguinis, as in the Greek case. Hence, many Argentine and Latin Americans acquired European nationality.

The mass naturalization of native persons in occupied territories is illegal under the laws of war (Hague and Geneva Conventions). However, there have been many instances of such illegal mass naturalizations in the 20th century.[citation needed]

Denaturalization is the reverse of naturalization, when a state deprives one of its citizens of his or her citizenship. From the point of view of the individual, denaturalization means "revocation" or "loss" of citizenship. Denaturalization can be based on various legal justifications. The most severe form is the "stripping of citizenship" when denaturalization takes place as a penalty for actions considered criminal by the state, often only indirectly related to nationality, for instance for having served in a foreign military. In countries that enforce single citizenship, voluntary naturalization in another country will lead to an automatic loss of the original citizenship; the language of the law often refers to such cases as "giving up one's citizenship" or (implicit) renunciation of citizenship. In another case, affecting only foreign-born citizens, denaturalization can refer to the loss of citizenship by an annulment of naturalization, also known as "administrative denaturalization" where the original act of naturalization is found to be invalid, for instance due to an administrative error or if it had been based on fraud (including bribery). In the US, the Bancroft Treaties in the 19th century regulated legislation concerning denaturalization.

Loss of U.S. citizenship was a consequence of foreign military service based on Section 349(a)(3) of the Immigration and Nationality Act until its provisions were found unconstitutional by the Supreme Court in 1967.[59]

Yaser Esam Hamdi was a U.S. citizen captured in Afghanistan in 2001. He was fighting against U.S. and Afghan Northern Alliance forces, siding with the Taliban. He was named by the Bush administration as an illegal enemy combatant, and militarily detained in the country for almost three years without receiving any charges. On September 23, 2004, the U.S. Justice Department agreed to release Hamdi to Saudi Arabia on the condition that he give up his U.S. citizenship, though since it was done under duress it is possible that he can later reclaim it.[citation needed]

Before World War I, only a small number of countries had laws governing denaturalization that could be enforced against citizens guilty of "lacking patriotism". Such denaturalized citizens became stateless persons. During and after the war, most European countries passed amendments to revoke naturalization.[63]

It is important to note that starting with the period of World War I, many European states began to introduce laws which permitted their own citizens to be denaturalized and denationalized. The first was France, in 1915, with regard to naturalized citizens of "enemy" origins; in 1922 the example was followed by Belgium, which revoked the naturalization of citizens who had committed "anti-national" acts during the war; in 1926 the Fascist regime in Italy passed a similar law concerning citizens who had shown themselves to be "unworthy of Italian citizenship"; in 1933 it was Austria's turn, and so forth, until in 1935 the Nuremberg Laws divided German citizens into full citizens and citizens without political rights. These laws—and the mass statelessness that ensued—mark a decisive turning point in the life of the modern nation-state and its definitive emancipation from the naive notions of "people" and "citizen"

The 1915 French denaturalization law applied only to naturalized citizens with "enemy origins" who had kept their original nationality. Later under Raymond Poincaré's government, another law was passed in 1927 which entitled the government to denaturalize any new citizen who committed acts contrary to the national interest.

In 1916, Portugal passed a law which automatically denaturalized all citizens born to a German father.

In 1922, Belgium enacted a law revoking the naturalization of persons accused of having committed "antinational acts" during the war; this was supplemented in 1934 by a new decree against people "in dereliction of their duties as Belgian citizens."

After 1926 in Italy, people who were deemed not to deserve the Italian citizenship or who were considered to represent a threat to the public order could lose their naturalization.

Egypt in 1926 and Turkey in 1928 enacted laws authorizing denaturalization of any person threatening the public order. Austria passed a similar law in 1933 by which it could denaturalize any citizen who participated in a hostile action against the state. Russia also passed several similar decrees after 1921.[63]

In 1933, Nazi Germany passed a law authorizing it to denaturalize any person "living abroad" and began restricting the citizenship rights of naturalized citizens of Jewish origin, followed in 1935 by citizens by birth on the basis of the Nuremberg laws.

During Vichy France, 15,000 persons, mostly Jews, were denaturalized (between June 1940 and August 1944), following the setting up, in July 1940, of a Commission charged of revision of naturalizations since the 1927 reform of the nationality law.[64]

In the United States, the proposed, but never ratified, Titles of Nobility amendment of 1810 would revoke the American citizenship of anyone who would "accept, claim, receive or retain, any title of nobility" or who would receive any gifts or honors from a foreign power.